Background <p>Brachial plexus birth palsy (BPBP) commonly leads to internal rotation shoulder contractures. Although aesthetically concerning, these contractures are functionally beneficial, particularly for facilitating hand-to-mouth movements. However, aggressive surgical corrections can paradoxically create more disabling external rotation–abduction deformities. We aimed to critically review the biomechanical, pathophysiological, and functional consequences of overcorrecting internal rotation contractures in BPBP and to evaluate strategies for management and prevention of iatrogenic deformities.</p> Methods <p>A narrative review of relevant literature, incorporating insights from advanced imaging, kinematic studies, and clinical experience, was conducted. Emphasis was placed on muscle imbalances, joint mechanics, and functional implications associated with excessive surgical release and reconstruction procedures.</p> Results <p>Overcorrection through tendon transfers, contracture releases, or clavicular/scapular osteotomies can disrupt the natural compensation mechanisms, especially scapulothoracic over glenohumeral motion. This leads to external rotation–abduction deformities characterized by impaired internal rotation, disrupted hand-to-mouth movement, and cosmetic and postural dissatisfaction. Imaging and motion analyses demonstrate underlying muscular and skeletal alterations predisposing to these outcomes. Internal rotation osteotomy is presented as a corrective option to restore humeral alignment and function.</p> Conclusion <p>Surgical intervention in BPBP requires a balanced, individualized approach. Preservation of functional internal rotation should be prioritized over cosmetic correction. Multidisciplinary evaluation and structured rehabilitation are critical in preventing and managing iatrogenic deformities. Internal rotation corrective osteotomy can be an effective salvage procedure when overcorrection occurs.</p> <p>Level of evidence: Not ratable.</p>